This image from the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter shows "Victoria Crater," an impact crater at Meridiani Planum, near the equator of Mars.Credit: NASA/JPL/UA.

NASA's
newest Mars orbiter has spied the plucky rover Opportunity perched
at the rim of the red planet's massive Victoria Crater as both vehicles explore
the fourth planet from the Sun.

Appearing
almost as a shiny boulder, Opportunity's lumpy outline and its camera mast shadow can easily be
seen in a high-resolution image of Victoria Crater taken by NASA's Mars
Reconnaissance Orbiter (MRO)and released by the space agency on
Friday.

"It is so
good to see that rover again," said Steve Squyres, the lead Mars Exploration
Rover scientist from Cornell University in Ithaca, New York, during a press
briefing. "I've got to say that image with that little rover 200 million miles
away, parked at the top of that cliff, that's just one of the most evocative images
I've ever seen in the planetary program...it's just beautiful."

At half a
mile wide (0.8 kilometers) and 200 feet (60 meters) deep, Victoria
Crater is large enough to fit up to five football stadiums inside and is
the biggest Martian crater to be visited by NASA's red planet rovers, mission
managers said.

"It's
probably the biggest crater we're ever going to get to with Opportunity, or in
fact with Spirit," NASA's Mars exploration program director Doug McQuistion
said during the briefing. "The bottom line is it gives us a window on the past of
the planet, and that's incredibly important to understanding why it is the way
it is and understanding relationships to potentially other rocky planets in the
Solar System."

Opportunity has
spent 21 Earth months exploring the Meridiani Planum region of Mars, eventually
working its way from its initial Eagle Crater landing site to Victoria. The
rover's robotic twin Spirit rolled
across its own Gusev Crater landing site, scaled
one of the region's Columbia Hills and clambered
down the other side. Together, the two rovers have produced some 160,000
images of the red planet.

"I think the
whole Mars Exploration Rover program is an example of NASA at its best," NASA
chief Michael Griffin said during the briefing today at the agency's Washington
D.C. headquarters.

Rover-orbiter
double team on Mars

The MRO
spacecraft's High-Resolution
Imaging Science Experiment (HiRISE) camera spotted Opportunity perched atop
a region known as Duck Bay at Victoria Crater during an Oct. 3 pass, when
mission controllers conducted the first test to physically aim the low-altitude
spacecraft at a specific target on Mars from an altitude of about 170 miles
(275 kilometers).

"We haven't
even begun the prime mission yet, that starts in November," said Alfred McEwen, MRO's
HiRISE principal investigator at the University of Arizona.

But MRO's Victoria
Crater images have already proved fruitful for Opportunity handlers, who are
eager to probe deep within the depression to get at the ancient layered rocks revealed
on outcrops and protrusions along the crater's wall.

"We're
extremely excited to see changes in the layering that we see in the outcrops,
because changes in layering mean changes in the environment," Jim Bell, lead
scientist for Opportunity's panoramic camera, said during the briefing.

New look
at old rocks

Early
estimates pin Victoria Crater at somewhere between 10 million and 100 million
years old, but the rocks within the depression themselves are likely much older
- as in a few billion years in age, researchers said. Since the crater is also
much deeper than any explored by Opportunity to date, the rover has an
unprecedented chance to uncover secrets of the region's distant past, they
added.

"For me,
this week has sort of felt like opening a book, like a mystery novel, where you
read the first few pages and you're hooked," Bell said. "We've just opened the
book on the story of Victoria Crater at Mars."

Opportunity
has already found
evidence that subsurface water once soaked rocks at Meridiani Planum based
on studies at Eagle Crater and the larger Endurance
Crater, both of which are dwarfed by Victoria's size.

Which
way to go

Squyres
said rover planners used MRO imagery as they planned Opportunity's short trip
from Duck Bay to a nearby bluff dubbed "Cape Verde" by mission team members. Victoria
Crater itself borrows its name from the single surviving ship - of a fleet
of five - of the historic Magellan expedition to circumnavigate the Earth in
the 16th century.

MRO's
detailed portrait of Victoria Crater, combined with panoramic images taken by Opportunity, will be the foundation from which Squyres
and his team shape the rover's partial trek around the depression's rim and,
eventually, the descent into the crater itself.

A complete
trip around the crater's 1.5-mile (2.5-kilometer) rim would take up to nine
months, and is likely unnecessary to obtain the needed data, mission managers
said, though a small crater named Sputnik just 60 feet (18 meters) is an
attractive target too.

"What we want
to do is find a safe path in and a safe path out...we don't want to make a
suicide dive into the crater," Squyres said. "We're going to do this safely, we're
going to do it carefully, we're going to do it when we're ready."

Rover
handlers must now balance safety with aggressive driving to get the most
science from what life Opportunity has left, Squyres added.

Opportunity is now into the 960th Martian day of a mission that
was initially planned to span just 90 sols, the term for days on Mars. Now pushing
more than 10 times its expected lifetime, Opportunity could fail at any moment,
and Squyres attributed the rover's longevity to a robust design and adept
handling by mission engineers and managers.

"You really
have to respect this landscape because it is a potentially very, very dangerous
place for the rover," Bell said. "We have goo-goo eyes about the potential of
what we can do, but we have to be very, very cautious."